A high carboydrate (CHO) high fiber diet and exercise have been promoted by health professional as an important way to prevent NIDDM or to help prevent the vast array of symptoms that result from the disease. We have demonstrated that regularly performed aerobic exercise improved glucose tolerance (OGTT), insulin stimulated glucose uptake and skeletal muscle GLUT-4 levels in older, glucose intolerant men and women. We propose to test the hypothesis that when subjects consume a high CHO, high fiber diet ad libitum, they will lose weight and demonstrate increases in glucose tolerance and insulin stimulated glucose uptake. We will also examine the effects of a hypocaloric (-500 kcal/d) high CHO diet alone and in conjunction with an aerobic exercise to produce an energy deficit. Specifically, we will examine body composition, insulin stimulated glucose disposal (during a euglycemic, hyperinsulinemic clamp), components of energy metabolism, muscle strength and power, maximal aerobic capacity and muscle metabolism (fiber type and size, glycogen synthase, glycogen content, GLUT 4mRNA) before and after 3 months of weight loss. This study will be the first to examine metabolic effects of an ad libitum and a hypocaloric high CHO diet (with or without exercise) in the elderly. The proposed studies will have important implications for the treatment of obesity and its vast array of complications that are often seen in older men and women.